Postsynthetic Strategy To Prepare ACN@Cu-BTCs with Enhanced Water Vapor Stability and CO2/CH4 Separation Selectivity

Cu-BTC, a commercially available MOF with great potential in gas adsorption and separation, is vulnerable to moisture, hindering its practical application. We propose a postsynthetic strategy to prepare ACN@Cu-BTCs with enhanced water vapor stability and CO2/CH4 selectivity. Successful grafting of ACN was evidenced by FT-IR spectra, which completely inhibited the moisture-induced adsorptive capacity degeneration of ACN1/1@Cu-BTC at RH = 55% for CO2 capture. The water vapor stability experiments showed that after being exposed to 55% RH for 20 days, Cu-BTC lost its crystallinity and CO2 adsorption capacity, while ACN1/3@Cu-BTC preserved 88% of its original CO2 capacity. In addition, ACN1/3@Cu-BTC showed a high CO2 capacity of 4.32 mmol/g under ambient conditions and inherited the decent CO2/CH4 adsorption selectivity from Cu-BTC. DFT calculation ascribed such an enhanced water vapor stability to the protection of Cu sites by ACN, which is worth further exploitation in enhancing the water vapor stability of...